Tired motor

[PeteG41]

If they vanish into the firewall, at least one of them is the vacuum control for the heater/air conditioner controls.

Okay I assumed they were for something like that. The other ones that I circled I think I can get rid of. I have one opening on those plastic T’s that I need to cap, but I think I’ll just get rid of all of them and them and cap it at the source. Pretty sure they are unused emission lines. Also looking into an EGR delete for the back of the carb. I’m assuming it would need some sort of block off plate but I haven’t dove into it too much. I got new plug wires and am going to use that diagram to clean them up. Looks like a rats nest of plug wires.

 

[RC92234]

Okay I assumed they were for something like that. The other ones that I circled I think I can get rid of. I have one opening on those plastic T’s that I need to cap, but I think I’ll just get rid of all of them and them and cap it at the source. Pretty sure they are unused emission lines. Also looking into an EGR delete for the back of the carb. I’m assuming it would need some sort of block off plate but I haven’t dove into it too much. I got new plug wires and am going to use that diagram to clean them up. Looks like a rats nest of plug wires.

Vacuum diagrams have been posted many times — I’d check before wholesale disconnecting hoses. The ports on the firewall are connectors to get engine vacuum other places, such as the HVAC canister.

 

[PeteG41]

Vacuum diagrams have been posted many times — I’d check before wholesale disconnecting hoses. The ports on the firewall are connectors to get engine vacuum other places, such as the HVAC canister.

Yessir, been browsing over the vac diagrams on here. Definitely not going to start doing line demo, just trying to really clean up the compartment. And in theory find possible vacuum leaks I have otherwise missed. Chomping on the bit to get this girl going, as you all can see. Just reminding myself its not an overnight thing.

 

[Hemikiller]

Mustang Barn has a fairly complete assortment of 73 vacuum diagrams on their site. The 73s are at the bottom of the page. If you still have the calibration code sticker on the engine, it'll tell you which one to use. Otherwise, look through and find the one that most closely resembles your setup.

https://www.mustangbarn.com/technical-information
The 4-way tree on the firewall is to supply manifold vacuum to the transmission vacuum modulator and the Air Conditioning system - if equipped.

Personally, I would go to the parts store and get an assortment of vacuum caps, and cap all ports on the intake and carburetor. You can then run the engine and see how it responds. If that smooths the engine out, you can start adding things back on to find the leak.

My first thought is your PCV valve is bad, or the hose split, or fell off the carb port.

Something specific to the 73s is the EGR valve. If that is stuck open, or the spacer has burned through (fairly common), it will mimic a massive vacuum leak.

 

[PeteG41]

Mustang Barn has a fairly complete assortment of 73 vacuum diagrams on their site. The 73s are at the bottom of the page. If you still have the calibration code sticker on the engine, it'll tell you which one to use. Otherwise, look through and find the one that most closely resembles your setup.

https://www.mustangbarn.com/technical-information
The 4-way tree on the firewall is to supply manifold vacuum to the transmission vacuum modulator and the Air Conditioning system - if equipped.

Personally, I would go to the parts store and get an assortment of vacuum caps, and cap all ports on the intake and carburetor. You can then run the engine and see how it responds. If that smooths the engine out, you can start adding things back on to find the leak.

My first thought is your PCV valve is bad, or the hose split, or fell off the carb port.

Something specific to the 73s is the EGR valve. If that is stuck open, or the spacer has burned through (fairly common), it will mimic a massive vacuum leak.

Awesome, thank you! I have some caps but after my last excursion through the motor I will need to get some more, used up pretty much all the smaller caps. I pulled the pvc valve out, and it rattles so I assume it’s good, but for $2 I might as well grab one. Forgive me if this is a dumb question, but I feel like there should be a small diameter vacuum line on the top part that I circled? And looking at the picture the connection from the pcv to the other line looks a little suspect. Is it possible to get rid of the egr? Couldn’t find a delete kit. Also didn’t realize until last night that the egr was attached to the spacer and would come off together if needed. Looking through the forum that spacer seems hard to find. I’m not worried about originality, would a different one work? And get rid of the egr all together.

 

[Steve McMahan]

Wait a minute, I rewatched the video: is that breather hose on the drivers side broken at that 90 degree PVC valve? It might be my bad eyes playing tricks on me. It that’s broken, you have a massive vacuum leak at that fitting. What do others see there?

 

[PeteG41]

Wait a minute, I rewatched the video: is that breather hose on the drivers side broken at that 90 degree PVC valve? It might be my bad eyes playing tricks on me. It that’s broken, you have a massive vacuum leak at that fitting. What do others see there?

I was trying to get a better picture but not currently home and had to screenshot it from a video. The line coming out of the 90 elbow is good at the connection. And the connection at the hard line to the back of the carb is good as well. From the picture it looked like it was split at the elbow but that hose is solid.

 

[rjcomp]

I know I have not touched mine in years but two things not mentioned that gave me headaches until I found causing mine to run simular to yours was the spark advande on the distributer. I could almost lift mine off. I know it is not what most look for. The other thing is that stupid nylon timing gear ford installed which wears out for most at about 50,000miles but a few get more miles. If you check the timing and see it bounce until you reach a steady speed then maybe you might check it.

 

[PeteG41]

I know I have not touched mine in years but two things not mentioned that gave me headaches until I found causing mine to run simular to yours was the spark advande on the distributer. I could almost lift mine off. I know it is not what most look for. The other thing is that stupid nylon timing gear ford installed which wears out for most at about 50,000miles but a few get more miles. If you check the timing and see it bounce until you reach a steady speed then maybe you might check it.

Will absolutely check that out. You guys have given me a ton of info on things to look for, it is very much appreciated. I am hoping when the motor was rebuilt the timing gear was replaced, but I really have no way of knowing that unfortunately.

 

[Ron Tanzi]

Will absolutely check that out. You guys have given me a ton of info on things to look for, it is very much appreciated. I am hoping when the motor was rebuilt the timing gear was replaced, but I really have no way of knowing that unfortunately.

I would bet that the timing chain set was changed to an all metal version when the engine got rebuilt. I don't think the original style nylon/aluminum cam gear has even been available for years.

Ron

 

[PeteG41]

Alright just to update you all on the saga of my 73 took a few vacation hours off work today to get some stuff done. Changed the plug wires, and wouldn’t you know it, 2 were loose. So right there was an issue. Changed out the rotor, and got some new points. I had cracked the cap open a while ago but didn’t look too much in depth. Well the points were gapped by Hellen Keller, as in pretty much no gap. I’m surprised it ran at all. Replaced those since they were a little burnt. She definitely idles 100x better, but still have a miss. Even still, makes me happy making improvements like that even if they are small. Next up will be the compression test, so I can figure out a plan.

 

[PeteG41]

Mustang Barn has a fairly complete assortment of 73 vacuum diagrams on their site. The 73s are at the bottom of the page. If you still have the calibration code sticker on the engine, it'll tell you which one to use. Otherwise, look through and find the one that most closely resembles your setup.

https://www.mustangbarn.com/technical-information
The 4-way tree on the firewall is to supply manifold vacuum to the transmission vacuum modulator and the Air Conditioning system - if equipped.

Personally, I would go to the parts store and get an assortment of vacuum caps, and cap all ports on the intake and carburetor. You can then run the engine and see how it responds. If that smooths the engine out, you can start adding things back on to find the leak.

My first thought is your PCV valve is bad, or the hose split, or fell off the carb port.

Something specific to the 73s is the EGR valve. If that is stuck open, or the spacer has burned through (fairly common), it will mimic a massive vacuum leak.

Have an update for you guys. I had this on a different thread when I posted a video of the motor, and was getting replies of either a dead cylinder or bad vacuum leaks. Since it had been sitting for 7 years or so, I changed the plugs, wires, cap/rotor, points, rebuilt the carb, and put in a new fuel pump. While it idled better, it still had a miss. Well, I heard back from my shop with the compression test and here's where we're at. I have no compression on 4 of the cylinders. They said its not all on one side, but I didn't ask which specific cylinders. I assumed I had at least 1 dead cylinder so at the end of the day 1 or 4 doesn't really matter in the grand scheme. Guess my original compression test was pretty accurate, I thought my gauge was a dud. Now I need to figure out what route I am going to go. Cheaper option is obviously pull the heads, have those machined and throw them back on. On the other hand, which I am about 95% leaning towards, is just rebuilding the whole thing. Looking at $5500ish, from a shop here in AZ. That includes pulling it and installation, as well as upgraded internals, melling oil pump, heads machined. So basically everything brand new. That way I know exactly what I am working with. Thoughts?

 

[Steve McMahan]

I posted on the other thread my thoughts, please find out what’s wrong before spending your hard earned money. 4 cylinders with no compression is hard to believe without major engine damage. And honestly, if you paid someone to do that test, please post the receipt so we can all learn the result of their diagnosis. Steve

 

[PeteG41]

I posted on the other thread my thoughts, please find out what’s wrong before spending your hard earned money. 4 cylinders with no compression is hard to believe without major engine damage. And honestly, if you paid someone to do that test, please post the receipt so we can all learn the result of their diagnosis. Steve

Yep I’m heading up there right now. First thing tomorrow morning I’m going to pop the valve covers off and take a look. I also find it hard to believe it ran/idled, let alone even drove, running on 4 cylinders. Will post an update once I get home

 

[will e]

Post up a new video of it idling too. While you have the valve covers off, spin the engine to TDC on the crank pully, look at cyl #1 valves to determine if either is compressed. If either is compressed, rotate the crank 360 degrees back to TDC. Confirm the orientation of your rotor that it is pointing at close to #1 cyl spot on the distributor when NEITHER #1 cyl valve is compressed. It's possible, although unlikely, that the timing is off 180 degrees. I've done this before and they will run but they run like crap and I got a lot of backfire through the carb. But it's a simple check while you have the valve covers off. (Remove the passenger side valve cover first, it's a bit easier to get to the bolts and then confirm your rotor is oriented correctly)

 

[mrgmhale]

Mustang Barn has a fairly complete assortment of 73 vacuum diagrams on their site. The 73s are at the bottom of the page. If you still have the calibration code sticker on the engine, it'll tell you which one to use. Otherwise, look through and find the one that most closely resembles your setup.

https://www.mustangbarn.com/technical-information
The 4-way tree on the firewall is to supply manifold vacuum to the transmission vacuum modulator and the Air Conditioning system - if equipped.

Personally, I would go to the parts store and get an assortment of vacuum caps, and cap all ports on the intake and carburetor. You can then run the engine and see how it responds. If that smooths the engine out, you can start adding things back on to find the leak.

My first thought is your PCV valve is bad, or the hose split, or fell off the carb port.

Something specific to the 73s is the EGR valve. If that is stuck open, or the spacer has burned through (fairly common), it will mimic a massive vacuum leak.

With permission from Mustang Barn I consolidated their bevy of 67-72 vacuum schematic PDF files into a single PDF file with the schematics grouped and sorted by year and engine size. I have found their vacuum system to be of value. And, of course I make my consolidated PDF file available on a no fee basis (also), just like Mustang Barn did for their individual files.

I had not noticed the 1973 schematics in the Mustang Barn offerings. I will go back to their site to see if I can find it. Meanwhile, in 1973 Ford finally got serious about providing vacuum line calibration info. Attached is a collection I put together that includes two 351 4v calibrations missing from the Shop Manual I have on file (Calibrations 3-15A and 3-16A).

My GoTo for some excellent, very cost effective PDF files for several manuals covering First Generation Mustangs, and more, is Forel Publications. Their web site is at:

https://www.forelpublishing.com/clickbank/index.html

 

[PeteG41]

With permission from Mustang Barn I consolidated their bevy of 67-72 vacuum schematic PDF files into a single PDF file with the schematics grouped and sorted by year and engine size. I have found their vacuum system to be of value. And, of course I make my consolidated PDF file available on a no fee basis (also), just like Mustang Barn did for their individual files.

I had not noticed the 1973 schematics in the Mustang Barn offerings. I will go back to their site to see if I can find it. Meanwhile, in 1973 Ford finally got serious about providing vacuum line calibration info. Attached is a collection I put together that includes two 351 4v calibrations missing from the Shop Manual I have on file (Calibrations 3-15A and 3-16A).

My GoTo for some excellent, very cost effective PDF files for several manuals covering First Generation Mustangs, and more, is Forel Publications. Their web site is at:

https://www.forelpublishing.com/clickbank/index.html

Fantastic stuff!! While I am saving up for the motor/tranny rebuild, I will definitely be going through these drawings!